Steam generator



May 31, 1932.

W. D. LA MONT QSTEAM GENERATOR Filed June 11, 1926 11 Sheets-Sheet lINVENTOR 14/4: 75/ DOUGLAS 1/7/7040" ATTORNEYS May 31,1932. w. D. LAMONT STEAM GENERATOR Filed June 11, 1926 ll Sheets-Sheet 2 I INVENTOR M475/? QOVEZAS [A lfo/vr BY I ATTORNEYJ May 31, 1932. w. D. LA MONT STEAMGENERATOR Filed June 11. 1926 11 Sheets-Sheet 3 INVENTOR il; 752001/5145 xi/71w;

ATTORNEYLS y 1932- w. D. LA MONT ,860,363

STEAM GENERATOR Filed June 11. 1926 ll Sheets-Sheet 4 fwd , INVENTOR14444715? 001/6243 ZA/Va/vr ATTORNEYS May 31, 1932. D LA M N 1,860,363

STEAM GENERATOR Filed June 11. 1926 ll Sheets-Sheet 5 m5 m2 m4 WWW /ATTORNEYS May 31, 1932. w. D. LA MONT STEAM GENERATOR Filed June 11'.1926 11 Sheets-Sheet 6 INVENTOR M44751? Dal/ems ZA/Ya/vr m wcfwATTORNEYLS y 1932. w. D. LA MONT I 1,860,363

STEAM GENERATOR Filed June ll. 1926 11 Sheets-Sheet 7 7M 7/ 7/74 I M5 M85% W :TTORNEYJ /77 i I... Q

May 31, 1932. w. D. LA MONT 1,850,363

' STEAM GENERATOR I Filed June 11. 1926 ll Sheets-Sheet 8 7 INVENTORM44753 Dauauas [Alien/r BY M r W A ORNEYcS May 31, 1932.

w. D. LA MONT STEAM GENERATOR Filed June 11, 1926 ll Sheets-Sheet 9INVENTOR M ALTE/E' 004164 AS [AM/v7 ATT R N EYJ May 31, 1932. w. D. LAMONT STEAM GENERATOR Filed June 11, 1926, ll Sheets-Sheet l0 INVENTOR#444 T5? flaw: ZA/Yo/vr BY Mw j ATTORNEY' May 31, 1932. w. D. LA MONTSTEAM GENERATOR Filed June 11, 1926 11 Sheets-Sheet 11 m W m T N mm m YM *A Patented May 31, 1932 UNITED STATES PATENT OFFICE WALTER DOUGLAS LAMONT, OF LARCHMOII'Z', NEW YORK, ASSIGNOR TO LA MON T v CORPORATION, ACORPORATION OF NEW YORK STEAM GENERATOR Application filed June 11, 1926.Serial No. 115,169.

This invention relates to the generation of steam or other vapors andhas for its object the generation of steam or vapor under diffcrcntpressures by generators which have a common series or series parallelwater 01' liquid circulation. Other and further objects and advantagesof the invention will appear from the detailed description whichfollows.

In my co-opending application, Serial No. 79,096, filed January 4. 1926,patented July 21,,1931, Patent No. 1,815,439 I have described steamgenerator installations in which generators of the film tube type whichis have been described in my prior Patent No.

1,545,668, dated July 14, 1925, and in my copending application, SerialNo. 32,064, filed May 22, 1925, are used in combination with boilers ofconventional designs to increase the efi'iciency of these installationsand to improve the operation and particularly the circulation of theconventional type boilers by connecting the positive circulation of thefilm tube generators in series. parallel, or series parallel with thewater mass of or the convection circulation in the conventional typeboilers. thereby not only increasing the overall cfliciency of theinstallation as a whole by adding highly efficient heat transfer surfacem in the form of film tubes which permit operation with a much lowerstack temperature than has hitherto been practicable but rendering theconventional type boilers themselves more efiicient as steam generators.The present invention is in part a continuation of my above referred toapplication. Serial No. 7 9.096, and embodies and includes improvementsin the general type of installation therein described, as well as otherfeatures of novelty.

According to the present invention, two or more generators are providedwith at least part of their circulation in common and the 5 installationis arranged so that steam or other vapors of different pressures can begenerated from the different generators without disturbing the commoncirculation of water or other liquid. One or more of the gen- }0 eratorsmay advantageously have positive. circulation. When one or morepositively circulated generators are combined accord-v ing' to thepresent invention, particularly Where a series or series parallel waterflow is provided, the circulation in all the generators is improved andthis type of arrangement constitutes the preferred broad embodiment ofthe present invention.

In the ensuing descriptions, I will refer to steam enerators and to thegeneration of steam, ut it should be understood that the oo presentinvention is equally applicable to the generation of vapors from anyliquid or any mixtures of liquids and that, therefore, the featureswhich are described in connection with the generation of steam are inthe main equally applicable to the generation of other vapors.

As the generatorhaving positive circulation, I prefer to use a film tubegenerator as described in my above referred to prior applications andpatent. In its broadest aspect, however, the present invention is notlimited to combined installations in which one or more La Mont film tubegenerators are utilized, and, on the contrary, any generator withpositive circulation may be substituted for the La Mont film tubegenerator with a corresponding decrease in heat transfer etliciency. Thefilm tube generator, however, presents so many advantages with regard toease of construction and installation, heat transfer efficiency and thelike, that it eonstitutes the preferred positive circulation generatorin installations according to the K present invention and while thebroad concept of the present invent-ion is notlimited to combinationsutilizing this type of generator, in its more specific aspects thecombination with one or more common typeszof convection circulatedboilers, operatinglto generate steam at different pressures, is an,important feature of the preferred embodiment of the present invention."

Under the term positive circulation include pumps of all kinds and otherdevices which positively and definitely circulate water. I do not, inthis application, claimthe use of generators in which a geyser ac-- tionis effected in the generating tubes, this forming part of thesubject-matter of my 00- application, Serial N 0. 116,305, filed 5 11 11 1926 patented Oct. l3, 1931, Patent No.1,82 7,244. 1

When twogenerators are to be operated at different ressures and a seriesor series parallel circisation of water through the generators is to'be, provided, it is. necessary to rovide two pressure transformers, oneto reguce the pressure of waterfed from the high pressure nerator to thelow pressure enerator an one, to'increase the presure o the water fedfrom the low pressure gfmngator into the high pressure generator. latterpressure transformer must, of necessity, be a positive circulationmeans; that is to say, a means which adds energy to the'mediumcirculated. This means is usually one or more pumps, in series or inparallel. The pressure transformer for reducing feed pressure from thehigh pressure generator to the low pressure generator may be a simplethrottling device in which pressure reduction is effected by the speedof flow of the water or energy absorbing means such as water turbinesand the like ma be used in order to bring about the desireequalizatlonjof pressure. In many cases where the high pressuregenerator is much smaller in capacity than the low pressure generator, athrottlevalve may be unnecessary as a pipe connection of small size mayexert sufiicient throttling action and minor variations will becompensated for by the large volume of water in the low pressuregenerator. valve is omitted it should be understood that the feed tubeitself is acting as a throttle or pressure transformer.

Connection between the two generators may be entirely in series, that isto say, all of the circulating water is circulated in series throughboth generators or a series parallel arrangement can be provided wherebyall of the water in one generator is circulated in series through theother generator but this water does not include the whole of thecirculating water in this latter generator. In some cases, a completeseries circulation is not necessary or desired and either the high orlow pressure boiler may be caused to feed water into the other withoutany return. Thus, the low pressure generator may act to heat the feedwater for the high pressure generator in addition to its function as asteam generator and conversely, of course, the high pressure generatormay feed into the low pressure generator through a. suitable throttlevalve.

The heating gas flow through the generators can be in various forms.Thus, for example, the gases may circulate first through one generatorand then through a second and may strike either the high pressuregenerator first or the low pressure generator first. Parallel gas flowthrough the two generators is also possible and frequently desirable andWhere a throttle flows can be used and may be desirable under certainstructural or operating conditions.-

Se arately fire generators may also be used, an as a matter of fact,they can be considered really as a special case of pure arallel gas flowsince it is thermally, alt ough not structurally, immaterial whether twogases are generated by separate flames or whether a single flame is usedand the gases are divided into two parts. Accordingly hereafter the exression parallel flow of heating gases Wlll be used to include separatefiring of the generators as well as utilizing part of the gas from asingle fire for one generator and part for the other.

While the invention is not limitedto any particular heating gas flow orto any'particular combination, for certain purposes a series flow ofheating gases possesses notable economic and thermodynamic advantages.Thus, for example, a film tube generator can be easily and simplyinstalled in the stack of an ordinary generator furnace which positionis particularly advantageous as it permits the use of very long tubeswith a corresponding high efiiciency in the film tube generator. Owingto the fact that the film tube generator has a very high heat transfercapacity, it is easily possible in most cases to produce a zero heathead or a heat head actully less than zero. That is to say, the stackgases, on leaving the film tube generator, may be reduced to atemperature equal to that of the steam generated or even less, since thewater circulation in a film tube generator is from top to bottom and is,therefore, counter to the gas flow, making it possible in some favorableinstallations to bring down stack temperatures to a oint intermediatebetween the temperature 0 the steam generated in the film'tube generatorand the temperature of the water introduced into the top of the filmtubes. Such an arrangement is structurally and thermally very efficientand advantageous and is included as a specific feature of novelty of thepresent invention in some of its preferred embodiments.

The film tube generator and analogous positive circulation generatorsmay be used as the high pressure or low pressure members.

When used as the low pressure member in the coldest heat zones with aseries heating gas flow, the greatest thermal efilciency can be achievedand this arrangement is peculiarly suited to the structural features ofthe film tube generator which requires forgreatest efiiciency long,small tubes, readily fitting into the stack of boiler furnaces. On theother hand, the small tubes and high heat transfer capacity of film tubegenerators make them peculiarly suitable for generatinghigh pressuresteam, particularly where they are placed in the hottest zone of thefurnace. When so placed, the thermal efliciency of the wholeinstallation is decreased, if the generator in the low temperature zonesis of the convection type. However, the structural and operatingadvantages of the film tube generator when used to generate highpressure steam in zones of high heat, may, and frequentl will renderthis arrangement very desira le even though it maybe necessary in somecases to sacrifice some thermal efii ciency due .to higher stacktemperatures. \Vhere a plurality of film tube generators are used, somein hot zones and others in cold zones, of course, there is no loss inthermal efficiency and the advantages of the film tube generator bothfrom the standpoint of low heat head and high steaming capacity may beenjoyed. It should be understood that in every case it is necessary tomake some compromise between ideal thermal efiiciency and structural andeconomic factors. The best compromise for any particular plantinstallation may be determined by the engineer designing theinstallation and itis one of the. important advantages of the presentinvention that it is applicable to a wide variety of installations andthis flexibility of arrangement and construction makes it possible tore-design existing boiler units with a minimum of rebuilding and to soincrease the efficiency of the installation as to, in many cases,add-years of life to obsolescent units, which, however, frequentlyrepresegit a very large capital investment.

The present-invention is also of importance in connection with waterwalls; thus, for example, a film tube generator arranged as a water wallcan be used very effectively for the generation of very high pressuresteam, as it is exposed to the radiant heat of the flame andpossesses,therefore, a very great steaming capacity while the highheattrans fer efliciency of the generator adds a very desirable factorof safety against burning out. Installations in which one or moregenerators are operating as water walls are included in the presentinvention and are important embodiments thereof.

While the present invention is particularly concerned with installationsin which a film tube generator is associated in series with a generatorof the convection circulation type, it should be understood that twofilm tube generators can be connected together according to the presentinvention in order to generate steam of different pressures. Suchinstallations can frequently be very efliciently arranged and where thedifference in pressure is not too great, the drop in pressure throughthe injection orifices of the low pressure film tube generator may, inmany cases, be sufficient to efi'ect the desired drop in pressurebetween the two generators. In other cases, additional throttle valvesmust be provided and can be with advantage controlled by the amount ofsteam generated in the low pressure generator by various control meanssuch as water level controls and the like. A similar automatic controlthrottle many common accessories such as safety valves, blow-offs andthe like have been omita ted in some cases and it should be understoodthat the drawings which are simplified to bring out the fundamentals ofthe present invention arenot to be considered as limiting the inventionto generators as illustrated, and, on the contrary, all the usualaccessories will be employed wherever they are desirable.

The drawings also show various circulation features associated withdifferent-types of conventional boilers. It should be understood thatthe association of one type of gas or water circulation with aparticular type of conventional boiler in no sense limits the invention,as the drawings have merely been chosen to illustrate the most importanttypes of circulation and a number of conventional boilers have been usedin these illustrations in order to show the applicability of the presentinvention to these various types of, boilers. It should be understoodthat features of flow shown in one figure as associated with "one typeof common boiler may be used with other types of boilers shown in otherfigures with a different type of circulation and vice versa.

The boilers of the present invention are illustrated in a purelydiagrammatic form in the drawings, in which Figure 1 is a sectionthrough two La Mont boilers showing cross feed from the low pressure tothe high pressure boiler without return,

Figures '2 and 3 are sections through high pressure inclined water tubeboilers associated with low pressure La Mont boilers, Figure 2illustrating cross feed from the low pressure to the high pressureboiler and Figure 3 series parallel circulation through the two boilers;v

Figure 4: is a section showing a combination of a high pressure La Montboiler, having tubes placed in the fire tubes of a low pressure firetube boiler;

' Figure 4a is a horizontal section along the line ia-4a of Figure 4;

Figure is a section showing a combination ofa bent tube cross drumboiler with a low pressure La Mont boiler illustrating cross sin 1e passwater tube boiler associated with I I feed from the high pressure to lowpressure rately fired high pressure La Mont boiler;

Figure 9 is a section through an Edgemoor hig pressure La Mont waterwall boilers;

Figure 10 is a section through three La Mont generators illustrating apure series flow.

Figure 11 is a section through two inclined tube water tube boilershaving a series gas flow Figure 12 is a section throu h a multiple unitLadd type. water tube boi or associated with a high pressure La Montgenerator;

Figure 13 is a section through a cross drum inclined water tube boilerassociated with two La Mont generators with parallel and series gas flowrespectively; and Figure 14 is a detail in perspective showing one ofthe headers broken away to show the jet orifices.

In the construction'shown in Figure 1 two separate La Mont generatorsconsisting in upper headers 1 and 2, lower headers or pots 3 and 4 andtubes 5 and 6 are arranged in the same furnace. Each generator has anindependent circulating system. Thus, water and steam discharged fromthe lower header 3 flow through the pipe'7 into the pot 8, where steamis separated and taken off through the pipe 9 provided with a valve 10and the water ows through the pipe 11, pump 12 and pipe 13 into theupper header 1, thus completing the circuit for the high pressureboiler. Suitable valves 14 and 15 may be provided to rogulatethe flow inthis circuit. In a similar manner the steam and water discharged fromthe lower low pressure header 4 flow through the pipe 16 into the pot 17where steam is separated and passes off through the pipe 18 controlledby the valve 19 and the water separated flows through the pipe 20, pump21 and pipe 22 to the upper low pressure header 2. A completecirculation is therefore provided for each boiler.

In addition to the separate circulations for the two boilers a pipe 23,provided with a valve 24, connects the water space of the-high pressurepot 8 with the water space of the low pressure pot 17 and water tends tofeed through t is pipe into the low pressure circulating system. Theflow of water is controlled by the valve 24 which is in turn actuated bythe water level control 25 on the pot 17, the amount of water fed beingadjusted to the evaporation of the low pressure boiler. Feed water for.both boilers is taken in 1,seo,aes

through a pipe 26 controlled .by a valve 27 which is actuated by thewater level control 28 on the high pressure pot 8. All of the feed forboth boilers therefore is introduced into the high pressure system andis controlled both by the evaporation of the high pressure generator andby the amount of feed which passes from the high pressure pot to the lowpressure pot.

Gas flow through the two boilers is in series, first through the highpressure boiler and then through the low pressure boiler, resulting in avery economical action since the highly efficient heat transfer of thefilm tube generators brings the temperature of the gases substantiallydown to thetemperature of the low pressure steam generated in the tubes6. A single feed passes directly into the high pressure circulation andsupplies both high pressure and low pressure generators with the amountof make-up water needed. The feed from the high pressure pot to the lowpressure pot is automatically adjusted in accordance with the steamdemands of the low pressure generator and in fact, actually enhances thesteam capacity of this latter unit, since the water in the pot 8 mayfrequently be at a temperature above the boiling point of water underthe pressure existing in the pot 17. Accordingly when the pressure isreduced in passing from pot 8 to pot 17 through the throttle valve 24,steam is formed which is added to the amount of low pressure steamgenerated by the low pressure boiler and passes oil through the pipe 18.The operation of the two boilers is independent of their relative steamdemands and the feed is automatically proportioned to the boilers in.accordance with their demand, a steady uninterrupted feed is obtainedirrespective of the relative steam demands on the two boilers and a veryeflicient utilization of the heating gases is achieved.

y In the drawing, the feed is shown as introduced in to the suction ofthe La Mont circulating pump. This is a convenient and advantageouslocation for feed introduction, but the feed can be introduced into anyother portion of the outside circulation of the La Mont generator orfeed can be introduced into the high pressure water tube boiler.

Instead of feeding water from the high pressure unit to the low pressureunit the converse is also possible and is frequently desirable. Thisflow is shown in Figure 2, where a low pressure La Mont generatorconsisting in upper header 2, lower header 4 and tubes 6 is arranged inthe stack or flue of an inclined tube boiler operating at a higherpressure. The water tubes are shown at 29 passing from rear headers 30to front headers 31. The drum 32 is connected to the front headersthrough the pipes 33 and to the rear headers through the pipes 34,completing the circulating circuit of the boiler. The circula is heatedup so that the Water tube boiler 013- tion of the La Mont unit is fromthe header 4 through the pipe 16 to the pot 17 and thence through thepipe 20, pump 21 and pipe 22 back to the upper header 2. Steam is takenoff from the pot through the pipe 18 controlled by the valve 19. Part ofthe excess water of the La Mont circulation is pumped fromthe waterspace of the pot 17 into the back header of the high pressure boiler bymeans of the pump drawing water through the pipe 36, and discharging itthrough the pipe 37, valves 38 and 39 being provided in the respectivepipes for control.

Feed water for both boilers is injected into the circulation of the LaMont boiler through thefeed pipe 40 controlled by the valve 41 which, inturn, is actuated by the water level control 42. In operation all of thefeed water for both boilers is circulated through the low pressure LaMont boiler and crating at high pressure receives only heated feedwater. The La Mont generator, therefore, not only serves the purpose ofan efiicient source for low pressure steam but it also serves to heat upall of the feed water which is introduced'intothe high pressure boiler.Owing to the largeamountiof cold feed water which is injected into thecirculation of the La Mont generator, thetmperature of the water in theupper header2 is comparatively low. and it is therefore readily possibleto operate with a heat head on the La Mont tubes which is less thanzero; that is to say,

I the stack gases after leaving the La Mont generator are at atemperature below that of the low pressure steam generated. p

In addition to increasing the over-all efiiciency of the boilerinstallation by generating low pressuresteam by means of what may reallybe considered as thewasteheat from the high pressure boiler, andparticularly in carrying stack temperatures down'to an eX-- ceedinglylow point by operating theLa Mont generator as a feed water heater aswell as a gcnerator,.a further advantage is inherent in the constructionshown in Figure 2, namely, the increased efficiency of circulation inthe water tube boiler.

The water injected through the pipe 37 possesses considerable velocityand can, if desired. be so directed as to flow into the water tubes inthe form of jets at considerable speed. A semi-injector action resultswhich greatly enhances the ef fectivencss of the ordinary convectioncirculation which exists in inclined tube boilers oi pressure La. Montgenerator and merely feeding the excess water into the hi h pressurewater tube boiler, a series para lel circulation is provided, waterunderhigh pressure being taken from the forward end of the drum 32, throughthe pipe 43, into the up per header 2 of the La Mont generator. In otherwords, the water for the La Mont generator is circulated through thewater tubes of the inclined tube generator and thence in series throughthe La Mont generator. This greatly enhances the circulation efiiciencyin the inclined water tube generator itself and at the same time omitsthe additional pump required in the modification shown in Figure 2 inorder to provide for a separate circulation in the La Mont generator.Feed can be introduced through the pipe 44 and the La Mont generator canbe utilized therefore as a feed water. heater as well as a generator,effecting the economical savings described in connection with themodification shown in Figure 2.

Figures 4 and 4a represent a very advantageous combination of a La Montgenerator with a relatively inefiicient and at the present time almostobsolete or obsolescent type of vertical fire tube generators. The firetube generator consists in a shell 45 extending down to form water legs46 and 47 separated by bafiles or partitions 217, and provided with firetubes 48'. The La Mont generator, which is operated at a higher pressurethan is the fire tube boiler, consists in an upper header 51, lowerheader 53 and tubes 55, which tubes pass through the fire tubes,resulting in a very markedly decreased hydraulic mean depth andincreased velocity of heating gases through the fire tubes. Steam andwater is discharged from the lower header 53 into pot 54, where steam isseparated, the steam passing oil through the pipe 49 controlled'by thevalve 50 and the water flowing into the leg 46 of the fire tube boilerthrough the pipe 52 provided with the valve 225, controlled by the waterlevel control 226. Water is taken from the leg 4. through the pipe56.and

pipe 49, the excess water flowing into the other leg of the fire, tubeboiler. Thus, the circulation of water through the La Mont generatorpasses in series through the fire tube boiler and enhances thecirculation of the latter in addition to Very greatly increasing theefiiciency of both units, due to the fact that the La Mont tubes passthrough the fire tubes and therebypermit a verylow hydraulic mean depthand high gas velocity with a correspondingly increased heat transferefficiency. Low pressure steam is taken from the fire tube boilerthrough the pipe 61 controlled by the valve 62.

In the modification shown in Figure 5, a low pressure La Mont generatorisinstalled -in the stack of a bent tubecross drum boiler .installationof the Stirling type, which boiler I in this modification operates at aconsiderably higher pressure than does the La Mont generator. heStirling boiler consists in upper .drums .63, 64 and 65 and lower drums66,

which is connected with the drum 63 by the J tubes 67 and to the drums64 and 65 by thetubes 68 and 69. Steam aces of the upper drums areconnected b t e tubes 70 and 71 and the water spaces 0 the drums 64 and65 are connected by the tube 72.

' The La Mont generator consists in upper header 73, lower header 74 andtubes 75. Water and steam from theheader 74 of the La Mont generatorpass through the pipe 76 into the not 77 where the steam is separatedand passes off through the pipe .78 controlled by the valve 79. Waterfrom the water space of the pot is pumped through the suction pipe 80,pump 81 and pipe 82 into the upper header 73, thus pI'OVldl% a separatecom lete circuit for the La ont generator. alves 83 and 84 control thespeed of circulation.

Feed water is introduced into the drum 63 of the Stirling boiler throughthe pipe 85 and the feed is controlled by the valve 86 actuated throughthe water level control 87 connected to the drum 64. Water is also fedfrom the drum 65 through the pipe 88 into the pot of the La Montgenerator andserves as make-up water to replace the steam generated inthe La Mont generator. The flow through the pipe 88 is controlled by thethrottle valve with a minimum of redesigning and rebuilding, and a largeincreased overall eflicienc-y results,,both from the more efiicientutilization of the heat in the heating gases and from the increasedcirculation in the Stirling boiler which correspondingly increases itssteaming capacity and im roves its operation. The water dischargethrough the pipe 88 is usually at a temperature considerably'above theboiling point corresponding to the pressure which exists in the 0t 77and therefore, a considerable amount 0 water is turned into steam andpasses oil as low pressure steam through the pipe 78. A sudden increaseddemand for low pressure steam, therefore, 1ow-.

' the result that an ad-v La Mont generator 0 small and economical size.Only a single pump'is used and the system is sun le andrelia'ble inoperation and lends ltsel tomany industrial applications.

A combination of. a Scotch marine boiler and a separately fired La Montgenerator is shown in Figure 6. The Scotch boiler which is ofconventional design, consists in'a shell 91 extending in the form of aleg 92 surrounding the firebox, and provided with fire tubes 93. Feed isintroduced through the pipe 94 controlled by the valve 95 and steam istaken oil from the steam space through the 'pipe 96 controlled by thevalve 97. The

Scotch marine boiler which may advantageously operate at a moderatesteam pressure is associated with ahigh pressure separately fired LaMont generator consisting in an upper header 219, lower header 220 andtubes 221, the circulation being from the header 220 through the pipe222 into the pot 223 and thence through the pipe 224, pump 98 and pipe99 into the upper header of the La'Mont generator. Valves 100 and 101are also provided for" controlling the flow.

In addition'to the separate circulations of v the La Mont boiler and theordinary convection circulation of the Scotch boiler means are providedfor feeding water from the leg 92 of the Scotch boiler into the pot 223by means of the pump 102 drawing water from the bottom of the leg 92through thepipe 103 and discharging it through the pipe 104, valves 105and 106 being provided for control purposes.

A relatively clean, hot feed is thus provided for the La Mont generatorwhich is advantageous when it is desired to generate large quantities ofhigh pressure steam in a La Mont generator of-economical size. Owing toits high heat transfer capacity it is also possible to use heat sourcesof great intensity without danger of burning out the tubes. Not only isa hot feed water of desirable purity assured for operation of the LaMont enerator at high pressure but the circulation 1n the Scotch marineboiler is very greatly enhanced as the flow through this boiler is fromthe feed pipe 95 backward and down through the leg 92 and then outthrough the pipe 103 into the pot of the La Mont generator. The flow ofwater thus roughly is counter to the flow of heating gases up throughthe combustion space and through the fire tubes resulting in aneffective heat transfer and decreasing the stack temperatures of theases leaving the Scotch boiler. This counter ow can, in some cases,materialas water walls or radiant heat boilers and an eflicient anddesirable combination of water wall boiler and conventional inclinedWater tube boiler is shown in Figure 7. In this figure, the water tubeboiler consisting-in a drum 107 rear header 108, front header 109 andtubes 110 and bafiies 111, preferably oper ates under moderate pressure,steam being taken oflf from the steam space of the drum through the pipe112 controlled by the valve 113. The low pressure La Mont water wallboiler consists in upper header 114, lower header and pot'115 and tubes116. High pressure water from the rear header 108'fl0WS to the header114 through the pipe 117 con trolled by the throttle valve 118. Afterpassing through the genei ator tubes 116, the mixture of steam and wateris separated in thepot 115, the steam passing ofl through pipe 119controlled by valve 120 and the water being pumped by the pump 121through the pipes 122 and 123 into the water s ace of the drum 107,suitable valves 124 an 125 being provided to control flow.

The La Mont generator, efiiciently shields the walls and serves as aneflicient source of low pressure steam. 'At the same time thecirculation through the main boiler is enhanced due to the fact'thatwater is pumped into one end of the drum and taken out from the rearheader 108'at the other end of the drum. 'A further important advantagelies in the fact that the danger of burning out the tubes '116 isminimized due to the fact that a large volume of high pressure water isavaiL able for feeding these tubes directly and is instantly controlledby the valve 118 which is actuated by the water level control 126. Thereis therefore, little or no danger of burning out these tubes even withvery marked and sudden variations in the temperature of the fire and inthe demandsffor .1; low pressure steam.

iii

If desired, the water wall can be operate as a full tube water wallinstead of a film tube struction may be cheaper and where the de mandfor low pressure steam is not'great, it may be economlcally advantageousto construct full tube water wall stead of film tube generators.

In Figure 8, a separately fired high pressure La Mont generator is shownassociated with an ordinary Wickes boiler designed to generate steam ata lower pressure. The lVickes boiler consists in an upper drum 127,lower drum 128 connected b rear circulating tubes 129 and frontcirculating tubes 130. A baflie 131 separates the two sets of tubes. Thesteam is taken 01f from the steam space of the upper drum through thepipe 132 controlled by the valve 133 and a feed pipe 134 generators, 1n-

-provided with a valve 135 is also connected to the water space of theupper drum. This feed pipe is used for auxiliary feeding, as will bedescribed below.

The separately fired high pressure La Mont generator consists in anupperheader 1 36, lower header-137 and generating tubes 138.

VVater and steam from the lower header 137- pass through the pipe 139 tothe pot 140,

valve 142. Excess Water from the water spaceof the pot is circulatedthrough the pipes 143 and 144 by the pump 145 which forces the waterinto the upper header136.

Valves 146 and 147 are provided to regulate flow and feed waterisintroduced through the pipe 148 controlled by the Valve 149,

which is actuated by the Water level control 158.

Some of the high pressure steam from the pot 140 is passed through thepipe Y150 and injector 151 where it picks up feed water from the tank152 through the pipe 153 and.

injects this feed water at high velocity through the pipe 154 andnozzles155 into the bottom of the water tubes 130 of the Wickes boiler,thereby very greatly enhancing the speed of circulationin the Wickesboiler and Q correspondingly increasing its steaming capacity. Theamount of feed water injected into the Wickes boiler by. the highpressure steam is controlled by means of the throttle valve 156 actuatedfrom the'water level control 157 associated with the upper drum of theW'ickes boiler. Feed .into the La Mont generator is similarly controlledby a water level control 158 associated with the pot 140.

In operation the circulation through the La Mont generator issubstantially inde endent from that of the Wickes boiler as ar as thewater is concerned, and high pressure steam 1 can begenerated in varyingamounts according to demand. The demand for low gressure steam fromtheWickes boiler prouces variations in thewater levelin the upper drumandthis in turn actua-tes the throttle valve 156, causing the injection ofthe necessary feed water by means of high pressure steam from theLa'Mont generator. Particularly where there isa large difference inpressures between'the two boilers a veryti l violent injection will takeplace and the naturally sluggish convection circulation of the \Vickesboiler is greatly accelerated. The

' of water in the Vickes boiler is not necessary, a. somewhat cheaperand simpler construct-ion-cau be used in which the nozzles arev omittedand the feed water is simply injected into the bottom of thedrum belowthe tubes 130. This will increase the circulation due to the fact thatthe velocity of the injected water continues into the circulating tubes.

The arrangement of a Wiclres boiler with a separately fired La Montgenerator is very flexible and the relative sizes of the two units canbe varied within wide limits. It is also possible to operate eithergenerator separately from the other; thus, for example, if connection tothe Wickes boiler is shut off by closing the valve 156 the La Montgenerator can be operated entirely independently and in the same way theVVickes boiler can als'obe operated independently, utilizing a separatefeed through the pipe 134 controlled by the valve 135. In some cases, itmay be desirable to provide a very small La Mont generator where thedemands for high pressure steam are low or the La Mont generator may berun at varying loads and. at times the steam production may beinsuflicientto inject suflicient feed water into the \Vickes boiler evenwhen the whole of the high pressure steam is used for this purpose. Thedeficiency can then be made up by introducing some additional feed waterthrough the pipe 134 if desired. In general, it should be understoodthat control of feed water which has been illustrated as automatic insome fi ures and as manual in others can be widely varied between thelimits of full automaticcontrol and full manual control.

The combination of two La Mont water wall generators for high pressuresteam with a lower pressure Edgemoor single pass boiler is shown inFigure 9. The front water wall consists in an upper header 159,generatingtubes 160 and lower header or pot 161 and the rear water wallsimilarly consists in an upper header 162, generating tubes 163 and alower header or pot 164. The Edgemoor boiler is provided with an uppersteam and water drum 165, a lower drum 166. generating tubes 167, a rearsteam and water drum 168, a water heater 169 and a superheater 170. Thesteam space of the drum 165 is connected to the steam space of the drum168 by means of the pipe 171 and the water spaces of these two aresimilarly connected by the tube 17 2. Saturated steam at low pressurecan be taken off through the pipe 173 controlled by the valve 174 or itcan be passed through the superheater passing out through thesuperheated steammain 175 controlled by the valve 176. Feed water isintroduced through'the pipe 177 controlled.

164 to the drum 166 of the Edgemoor boiler through the pipe 184controlled by the throttle valve 185. High pressure steam is taken offfrom the pots 161 and 164 through the pipes 186 and 187 controlled bythe valves 188 and 189. Valves 190 and 191 are also provided in thepipes 182 and 183 in order to control the delivery of water to the LaMont generators. These valves may be operated manually or, as shown inthe drawing, may be connected to suitable water level controls on thepots 161 and 164. These water level controls are shown at 192 and Inoperation feed water for both of the boilers is introduced through thepipe 177 heated in the feed water heater 169, whence it passes into thedrum 168 and down through the pipe 179. The pump then delivers the waterat a considerably higher pressure into the La Mont generators where partof the water is evaporated and steam and water are separated in the pots161 and 164. The excess water is then circulated through the pipe 184into the bottom drumof the Edgemoor boiler and-thence positively upwardthrough the generating tubes 167 into the upper drum 165, where steamand water are partially separated, the steam and water passing throughpipes 171 and 172 into the steam separating drum 168. The water thencirculates down through the pipe. 179 and again through the La Montgenerators.

It will be seen that the water circulation through the generators atdiiferent pressures is purely in series, every bit of the circulatingwater being required to pass through the generators at both pressures inseries. This provides for an extremely efiicient circulation through theEdgemoor boiler and very greatly increases its steaming capacity. At thesame time the large feed water heater of the Edgemoor boiler serves toheat up feed water for both the Edgemoor and the La Mont generators.Only a single pump is required in this system and yet a full positivecircula tion isassured in all three generators.

' Figure 10 illustrates three-La; Mont generhigh pressure generator.

ators arranged in series inthe same furnace and possessing a pure seriescirculation; The high pressure generator which is arranged in thehottest zone of the furnace con.- sists in upper header 194, tubes 195and lower header or pot 196. Correspondingly the intermediate pressuregenerator includes upper header 197, tubes 198 and lower header or pot199, whereas the low pressure generator which is in the coolest zone isshown as provided with upper header 200, tubes 201 and lower header orpot 202. Each of the pots is provided with steam pipes from their steamspace, the high pressure pot discharging high pressure steam through thepipe 203 controlled by the valve 204, the intermediate pot through pipe205 controlled by valve 206 and the low pressure pot through pipe 207controlled by valve 208.

Water from the low pressure pot 202 passes through a pipe 209 intoreservoir 227 from which it is drawn by pump 210 and forced through apipe 211 into the upper header 194 of the high pressure generator. Alarge excess of water is circulated through this generator, a certainamount being evaporated and the steam separated in the pot 196. Thewater which remains unevaporated passes then from the water space of thepot 196 through the pipe 212 into the upper header 197 of theintermediate pressure generator, whence it circulates down through thefilm tubes 198, a still further portion of water being evaporated andthe steam separated in the pot 199. The unevaporated water andalso somesteam passes from the water space of the pot 199 into a reservoir 8which is similar to that shown in Figure 1, where steam and water areseparated, the water passing thence through the pipe 213 into the upperheader 200 of the lower pressure generator, where a still further amountis evaporated and the steam separated in pot 202. The excess water isrecirculated through pipe 209 into reservoir 227 where any entrainedsteam is separated and passes into the steam main 207 through the pipe228. Feed water may be introduced into the reservoir 227 directly butpreferably such introduction is controlled by means of an injector 151operated from steam from the V This feed water is taken from a tank 152and passes into the system through the pipe 153 to an injector 151, thesteam for which is led from the reservoir 8 by the pipe 150. A waterlevel con- I trol 216 acts upon valve 215 in the pipe 150 posed to themost intense heat they receive the maximum protection. The intermediategenerator is correspondingly protected by its proportionate excess ofwater.

The drop in pressure between the generators is produced in themodification shown 1 in Figure 10 by the restriction of the inletorifices in the headers 197 and 200 when the difference in pressurebetween the various generators is not excessive. This arrangement isvery simple and economical, as it involves no moving parts or valves.

Owing to the fact that all the water is circulated in series through thethree generators a stoppage in either the high or intermediate pressuregenerators might cause the low pressure generator to run dry and burnout and in order to prevent this possibility by-pass pipes 216 and 217can be provided leading from the pump outlet to the upper headers 197and 200 and controlled by the valves 218'and 219. In case of a partialor total stoppage of flow'through the high pressure or intermediatepressure generator, one or more of these valves can be opened to producea parallel circulation through the intermediate or low pressuregenerators and prevent their burning out.

In a similar manner, these valves may be used to modify the pure seriescirculation and produce in part a series parallel circulation. This maybe desirable where the demands for low pressure or intermediate pressuresteam may vary and may, at times, be disproportionately large incomparison to the demands for high pressure steam. The exact combinationof controls, automatic, semiautomatic or manual, which is most desirableunder the operating conditions in any particular installation will, ofcourse, be chosen by the skilled steam engineer.

Figure 11 illustrates the combination of two inclined cross drum watertube boilers operating under diiierent pressures. The high pressureboiler consists in drum 229, front headers 230 and 231, rear headers and233, the headers being connected respectively by two decks of generatortubes 23% and 235. The upper rear header 232 is connected to the drum229 by the tubes 236 and the respective front and rear headers areconnected by the pipes 238 and 237. A superheater consisting in intakeheader 289, superheater tubes 240 and outlet header 241, is connected tothe steam space of the drum 229 by the pipe 242 and discharges highpressure superheated steam through the pipe. 243 into a

